On one hand I agree, but I don't think it would be worth it for every single buff you had.
Permanent buffs like auras are something that makes more sense above the champion portrait because they aren't going away anytime soon, while stuff like stacking buffs like stacks on Nasus' Siphoning Strike stack counter or Udyr's stance-specific buff (permanent buffs while in the stance like the Bear Stun, not upon immediately activating the stance like the Bear MS boost) could also remain there.
However, anything that needs to be kept track of on a constant basis should be on the main buff bar. I played a couple games with Nautilus in the new jungle, and at one point I was confused as to why my shield was visually up when it didn't come up in my buff bar, and then I saw it in the champ portrait buff bar. That kind of buff I really need on my main buff bar, not on the little buff bar.